1. Field of the Invention
The present invention relates to a poweroperated chuck, especially a hollow chuck that is provided with a central through-bore and is intended for use with numerically controlled turning machines.
2. Description of the Prior Art
Power-operated chucks are known, for example, from German Offenlegungsschrift No. 32 33 917 Rohs dated Mar. 15, 1984 and 32 41 590 Nobuoka et al dated May 10, 1984. To radially adjust clamping jaws to a clamping diameter desired at any given time, both of these heretore known constructions separate the actual clamping jaw from the driving jaw, and dispose a spindle between the jaw components. The spindles of all of the clamping jaws are adjusted simultaneously by a turning mechanism.
The drawback of these known constructions is that the entire clamping force must be transmitted to the threads via the spindles and hence via a linear contact. In addition, the turning or rotary drive mechanism closes off the central throughbore of the chuck that is required for a large number of clamping tasks, so that the heretofore known constructions are not suitable for use with hollow chucks. Finally, operation of an adjustment mechanism requires the use of a rotary drive mechanism that must rotate along with the chuck. This requires a considerable technical outlay, which is not only expensive but also does not operate precisely.
An object of the present invention, in a power-operated chuck, is to embody an adjustment member for shifting the clamping stroke within the clamping range in such a way that a radial adjustment is also possible, with little technical outlay, for one-piece clamping jaws of known construction, in order to achieve a high clamping force with a short clamping stroke and with great repetitive accuracy, whereby despite the use of a separate adjustment mechanism, the chuck is to be provided with a through-bore.